Process for producing monosodium glutamate



United States Patent 3,360,555 PROCESS FOR PRODUCING MONOSODIUMGLUTAMATE John A. Frump, Terre Haute, Ind., assignor to CommercialSolvents Corporation No Drawing. Filed Dec. 10, 1964, Ser. No. 417,50212 Claims. (Cl. 260-534) The present invention rel-ates to the recoveryof monosodium glutamate, and more particularly to the recovery ofmonosodium glutamate from zinc glutamate.

At present, monosodiu-m glutamate (MSG) is produced from zinc glutamate(ZnGA) by processes involving several steps wherein glutamic acid solidsare first produced and monosodium glutamate thereafter produced byreaction of the solids with sodium hydroxide.-It is an object of thepresent invention to provide a one-stage process for the recovery of MSGfrom ZnGA.

The recovery process of the present invention can be represented by theequation:

The reaction can be carried out by adding Na HP0 to a slurry of ZnGA andremoving the resulting ZuN-aPO H O precipitate by filtration. Monosidiumglutamate can be recovered from the filtrate solution by conventional,e.g. crystallization, techniques.

It is advantageous to perform the process with a slurry of ZnGA in waterto provide an aqueous solution adapted for crystallization of MSG.Quantities of water as large as desired may be used; however, it ispreferable to use from about 0.8 to about 1.6 milliliters of water pergram of ZnGA to avoid the expense of evaporating water prior tocrystallizatiin. The minimum amount of water necessary to obtain aworkable slurry is about 0.6 milliliter of water per gram of ZnGA. Also,preferably, the water is divided bet-ween the ZnGA and the Na HPO toprovide a convenient way of handling both reactants. Furthermore,stirring is desirable to insure thorough mixing of the reactants.

Na HPO is added to the ZnGA in an amount suflicient to convert the ZnGAto MSG. In general, amounts ranging from about 0.1 to 1.5 moles of NaHPO per mole of ZnGA is sufficient to convert the ZnGA into MSG which issoluble and ZnNaPO H O which is insoluble. Preferably approximatelystoichiometric amounts, i.e. from about 0.8 to 1.2 moles of Na HPO permole of ZnGA, are used since, if excess Na HPO is present, the MSGsolution will contain phosphate impurities which are undesirable,whereas if insufficient Na i-IP0 is added, some ZnGA will be carriedover with the insoluble ZnNaPO -H O so that valuable product will belost.

The temperature of the reaction is not critical. Temperatures from thefreezing point to the boiling point of water under ambient pressures,generally from about 0" to about 100 C., can be used and atmospheric, aswell as sub-atmospheric and super-atmospheric, pressures can be used. Itis advantageous, however, to utilize temperatures of from about roomtemperature, e.g. 20 to 25 C., up to about C. to enhance theinsolubility of the 3,360,555 Patented Dec. 26, 1967 It is advantageousto react the ZnNaPO4-H O produced, e.g. the filter cake, with sodiumhydroxide in order to recover zinc hydroxide and sodium phosphate, forexample, in accordance with the equation:

The precipitated zinc hydroxide can be recovered and used, for example,in the production of ZnGA by reaction with glutamic acid in afermentation medium. In general, to recover zinc hydroxide the ZnNaPO -HO is slurried with water and sufiicient sodium hydroxide added toprecipitate the insoluble zinc hydroxide which can be recovered byfiltration. Preferably, about two moles of sodium hydroxide are addedfor each mole of ZIINBPO4 H2O In general, this reaction may be carriedout at temperatures of from about 0 to about C. and at atmosphericpressures, super-atmospheric or sub-atmospheric pressures. The solubleNa PO can also be recovered from the filtrate by spray drying orevaporating to dryness. Additionally, the Na PO solution can be used toprovide MSG from ZnGA by adding H PO to the solution in an amountsufiicient to convert it to equivalent Na i-IP0 for use in the formationof MSG as discussed above. Na PO is a valuable by-product of the processand is used in detergent materials.

The following examples serve to further illustrate the inventionwithout, however, limiting the same.

Example I One mole of ZnGA (246.4 gms.) was slurried with mls. of waterand heated to 60 C. One mole of Na HPO (142 gms.) was dissolved in -60mls. of water, heated to 60 C. and added to the ZnGA slurry. Agitationwas continued for 30 minutes while maintaining the temperature at 60 C.The mixture was cooled to 25 C. and filtered. The filter cake was washedfive times with 25ml. portions of water. Combining the filtrate andwashes gave a total volume of 435 mls. containing 335 gms./literglutamic acid, with a pH of 7.0. This represents 99% recovery ofglutamic acid from ZnGA to MSG solution.

The MSG solution was decolorized with activated carbon and an ionexchange resin. Two volumes of ethanol were added and MSG crystals wererecovered by filtration. The crystals were 99.42% pure. Recovery fromZnGA to MSG crystals was 86%, with the balance remaining in thewater-ethanol filtrate where recovery could be made by recycling. TheMSG crystals contained 29 ppm. Zn. The product contained 112 p.p.m. P0,.

The filter cake from the original filtration weighed 199.5 gms. (dry).It contained 31.1% Zn and 47.4% P0 Theory for ZnNaPO -H O is 32.4% Znand 47.2% P0 'Ilhis represent 95% recovery of Zn from ZnGA to ZnNaPO -HO.

Example 11 One mole of ZnNaPO -H O (201 gms.) was slurried with 300 mls.of water and heated to 100 C. Two moles of NaOH gms. of 50% solution)were added and the temperature was maintained at 100 C. while agitatingfor 30 minutes. The reaction mixture was filtered at 100 C. and thefilter cake was washed with hot water. The dry cake weighed 80 gms. andcontained 74.8% Zn and 1.53% P0 representing about 96% conversion toZn(OH) which also contained about 1.3% of the original P0 present inZnNaPO -H O.

The Zn(OH) (80 gms.) was slurried with 300 mls. of water, 104 gms. of96% H 80 were added, and after the reaction was complete, the mixturewas filtered. The filtrate weighed 777 gms. and contained 7.67% Zn, or99.5% of the Zn originally present in the Zn(OH) The ZnSO solution issatisfactory for further use in the recovery. of glutamic acid as ZnGAfrom a fermentation medium.

The Na PO filtnate (872 mls.) contained 10.75% P; (98.7% of the originalP0 and is satisfactory for further use in the recovery of MSG from ZnGA.

It is claimed:

L A process for the recovery of monosodium glutamate from zinc glutamatewhich comprises adding Na HPO ,to an aqueous zinc glutamate slurry in anamount sufficient to precipitate ZnNaPO -H O, separating theprecipitated ZnNaPO -H O and recovering monosodium glutamate from thesolution remaining.

2. Process of claim 1 wherein said amount is from about 0.1 to about 1.5moles of Na HPO per mole of zinc glutamate."

3. Process of claim 1 wherein said amount is from about 0.8 to about 1.2m'oles N-a HPO per mole zinc glutamate.

4. Process of claim 1 wherein said slurry contains from about 0.8 toabout 1.6 milliliters of Water per gram zinc glutamate.

5. Process of claim 1 wherein the temperature is between about 0 and 100C.

6. Process of claim 1 'wherein the temperature is between about roomtemperature and 75 C.

7. Process of claim 1 further including the steps of slurrying saidZnNaPO -H O in Water, adding sufficient NaOH to the sl rry so producedto precipitate Zn(OI-I) 4 separating the Zn(OH) and recovering N-a POfrom the solution remaining.

8. Process of claim 7 wherein approximately two moles NaOH are added permole of ZnNaPO -H O.

9. Process of claim 7 wherein the NaOH is reacted with ZnNaPO 'H O at atemperature of from about 0 to about C.

10. Process of claim 7 wherein said N21 PO is converted to Na HPO by theaddition t hereto of H PO and the Na i-IP0 so produced used to produceadditional monosodium glutamate.

11. A process for the production of N a PO which comprises the steps ofslurrying said ZnN-aPO -H O in water, adding suificient NaOH to theslurry so produced to precipitate Zn(OH) separating the Zn(OH) andrecovering Na PO from the solution remaining.

12. Process of claim 11 wherein the NaOH is reacted with ZnN-aPO -H O ata temperature of from about 0 to about 100 C.

References Cited UNITED STATES PATENTS 3,278,572 1 0/1966 Frump 260-534XR LORRAINE A. WEINBERGER, Primary Examiner.

A. P. HALLUIN, Assistant Examiner.

1. A PROCESS FOR THE RECOVERY OF MONOSODIUM GLUTAMATE FROM ZINCGLUTAMATE WHICH COMPRISES ADDING NA2HPO4 TO AN AQUEOUS ZINC GLUTAMATESLURRY IN AN AMOUNT SUFFICIENT TO PRECIPITATE ZNNAPO4.H2O, SEPARATINGTHE PRECIPITATED ZNNAPO4.H2O AND RECOVERING MONOSODIUM GLUTAMATE FROMTHE SOLUTION REMAINING.
 7. PROCESS OF CLAIM 1 FURTHER INCLUDING THESTEPS OF SLURRYING SAID ZNNAPO4H2O IN WATER, ADDING SUFFICIENT NAOH TOTHE SLURRY SO PRODUCED TO PRECIPITATE ZN(OH)2, SEPARATING THE ZN(OH)2AND RECOVERING NA3OH4 FROM THE SOLUTION REMAINING.
 10. PROCESS OF CLAIM7 WHEREIN SAID NA3PO4 IS CONVERTED TO NA2HPO4 BY THE ADDITION THERETO OFH3PO4 AND THE NA2HPO4 SO RPODUCED USED TO PRODUCE ADDITIONAL MONOSODIUMGLUTAMATE.